North Korea launched a ballistic missile Sunday morning from a site north of Pyongyang, South Korea's military said, as President Moon Jae-in immediately convened an emergency meeting of the National Security Council (NSC) to discuss the issue.

"North Korea fired an unidentified missile at around 5:27 a.m. today from an area in the vicinity of Kusong, North Pyongan Province," the Joint Chiefs of Staff (JCS) said in a statement

The projectile flew some 700 kilometers, it said, adding it's analyzing more details.

The flight distance suggests the success of the missile test, the North's first military provocation since the inauguration of Moon last week.

North Korea fires a medium-range ballistic missile in February in this file photo. (For Use Only in the Republic of Korea. No Redistribution) (KCNA-Yonhap)

The U.S. Pacific Command, based in Hawaii, also announced that it detected and tracked the launch of the missile, which landed in the East Sea.

"The type of missile is being assessed and the flight was not consistent with an intercontinental ballistic missile," it said. "U.S. Pacific Command is fully committed to working closely with our Republic of Korea and Japanese allies to maintain security."

The Japanese government said the North's missile flew for half an hour. Prime Minister Shinzo Abe criticized the North for again violating the U.N. Security Council resolutions.

Moon, South Korea's new leader, is presiding over the NSC session that started at 7 a.m, according to his office Cheong Wa Dae.

The JCS said, "Our military is maintaining a full defense posture, closely monitoring the North Korean military's move."

The North test-fired a Pukguksong-2 intermediate-range ballistic missile (IRBM), also known as KN-15, from the same site on Feb. 12.

Sunday's launch was the North's first-known missile test in two weeks. (Yonhap)